Well, If you weren't hreatening we could have worked it out. By the way, you took back and replaced the tuner because the one you advertised said it was in perfect working order. Obviously, you must retain your 100% feedback record on ebay, which is a joke in itself. Anyhow, it was not unreasonable for me to suggest that you have an estimate. It could be really something very minor. I can not undertsand how you would not do that. I just think you didnt want the radio and felt you apid too much ...
Perhaps I'll regret butting into into a personal fight, but oh, well, I tend to do some silly things sometimes.
Some observations: If someone buys something from you and it's defective, their attitude afterward is irrelevant. Anyone who's ever run a business knows that customers who get something defective are always upset and you can't hold it against them. Of course they're upset. You've just sold them the reason! Your only rational, responsible and ethical response is to fix the problem. If they're still upset after you replace, repair or accept the return of the defective product, then sure, perhaps you're dealing with someone who's just plain difficult. But when I hear someone saying, in effect, I'd have fixed it if you weren't so upset, it sounds to me like they were just looking for an excuse not to fix it no matter what.
If the problem appears to be damage in shipping and you were the one who packed it, insured it and shipped it, it's your responsibility, not anyone else's, to get estimates or whatever it is you think should be done. Anyway, since it was you, not the recipient who entered into the contract with the shipping company, you're the only one from whom the shipper will even accept a complaint. The recipient's only responsibility -- all he can do! -- is to make the product and all the shipping materials available to the investigator the shipping company will send out to review the matter.
Finally, belittling someone's pride at achieving a record of 100% satisfied customers makes it sound like you don't think having people you do business with walk away satisfied is very important. It sounds like you're saying that you think the best strategy is, once you get the money, screw 'em since the whole point -- the only point! -- is to get the money. You should know this does not paint a flattering image of you.
Free advice, but my own experience in business is that for every customer who tells you someone you didn't want to hear, there are probably 10 more who felt the same but decided simply to walk away rather than fool with you again. Your most important customers are the ones who complain because they tell you things you need to know about what you're doing wrong if you want to succeed (in business and in life.)
You'll do whatever you want, obviously, but if it was me, I'd contact the shipping company to have them investigate but be prepared to have them come back and report that the unit was improperly packed and not their responsibility. Regardless of whether I was ever going to see a dime from insurance, I'd send out a call tag to have the unit returned to me at my expense and I'd refund the payment I'd received. Since, as you point out, you have so much money you could buy your customer 100 times over, this should not be a problem for you.